The present invention relates to a plant operation monitoring system, and particularly relates to an alarm display processing system for automatically selecting important alarms among a large number of alarms generated from the monitoring system and displaying the important alarms, and also relates to an apparatus for giving alarm selection standards to the system.
In various types of large-scaled plants such as a nuclear power plant, a chemical plant, a thermal power plant, a hydraulic power plant and the like, various systems are provided for the safe and stable operation of plant. As one of the systems, an alarm display processing system is an important system having a function of displaying the abnormal state of the plant. When, for example, a failure arises in a nuclear power plant, the alarm display processing system may output hundreds of alarms almost simultaneously correspondingly to the degree of the failure. Even in the case where such a large number of alarms are generated, an operator must judge experimentally the most important alarm among the large number of alarms at that point of time.
If, in this case, an alarm display processing system having a function of judging truly important alarms to display them without display of other alarms derived therefrom can be provided, the operator can grasp the state of the plant easily so that the system is very useful to the operator.
For example, in the case of a technique described in JP-A-64-12395, when alarms are generated, important alarms are decided by retrieving the cause and result of alarm generation from a knowledge base constituted by knowledge with respect to the attributes of alarms and knowledge with respect to the cause of alarm generation and the importance of alarms.
For example, in the case of a technique described in JP-A-63-282505, when a signal indicating plant abnormality is generated, an alarm corresponding to an initial event as the cause of signal generation is generated through deciding the initial event to guide an operating rule corresponding to the initial event to the operator.
In the technique described in JP-A-64-12395, important alarms are retrieved from generation alarms by an inference function. If the inference mechanism is operated to judge important alarms, a large processing time is required so that important alarms are not outputted just after the generation of alarms but are outputted after the passage of time of from the order of several seconds to the order of tens of seconds. This time lag is undesirable because the operator must grasp the state of plant just after the generation of alarms. Furthermore, in the conventional technique, the degrees of importance of alarms are set preliminarily but the degrees of importance may be changed according to the state of plant. There arises a problem in that it is impossible to set the degrees of importance to all alarms preliminarily.
In the technique described in JP-A-63-282505, the initial event is specified so that alarms other than alarms corresponding to the initial event are suppressed as derivative alarms. It is however difficult to specify the initial event at the time of occurrence of abnormality, because the initial event can be generally found by examination after the failure plant is stopped. Of course, if the initial event can be specified at the time of occurrence of abnormality to thereby generate an alarm corresponding to the initial event, a very excellent alarm processing system may be provided. In the present state, the initial event is obtained by an inference function in the same manner as the conventional technique, so that there arises a problem in that an impractically large time is required.
As one of conventional techniques, a system for deciding the initial event after deciding the correspondence of cause and result between alarms at the time of occurrence of abnormality in plant has been described in JP-A-64-91211.